Reproduction Flashcards
(26 cards)
How is the ovarian cycle established at puberty?
Leptin from adipose tissue decreases hypothalamic estrogen sensitivity
Presence of GnRH causes release of LH and FSH
Adult cyclic pattern is achieved in ~4 years and menarche occurs
What happens to hormones during the early to mid-follicular phase?
Thecal cells (acted on by LH) produce androgens, which act on granulosa cells Granulosa cells (acted on by FSH) convert the androgen into estrogen
What happens to hormones during the late follicular phase and ovulation?
Estrogen rises due to the positive feedback loop
LH, FSH and estrogen levels spike– LH surge is the reason ovulation occurs
What happens to hormones during early to mid-luteal phase?
Highest progesterone levels during this phase, will stay high for as long as the corpus luteum is there
What happens to hormone levels during the late luteal phase?
Decrease in estrogen and progesterone levels
What is the major source of estrogens, progesterone and testosterone?
Estrogen and progesterone: ovary
Testosterone: testes
What feedback effect does estrogen have?
Negative and positive feedback on gonadotropin release by anterior pituitary and GnRH release by the hypothalamus
What feedback effect does progesterone have?
Negative feedback on gonadotropin release and GnRH release
What feedback effect does testosterone have?
Negative feedback effect on gonadotropin release and GnRH release
What hormone is responsible for female and male libido?
Female: estrogen
Male: testosterone
What are the three phases of the menstrual cycle?
Day 1-5: menstrual phase
Day 6-14: proliferative phase
Day 15-28: secretory phase (constant 14 day length; =luteal phase)
Describe the menstrual phase
Ovarian hormones at their lowest levels
Gonadotropins begin to rise
Stratum functionalis is shed and menstrual flow occurs
Describe the proliferative phase of the uterine cycle
Estrogen levels prompt generation of new functional layer and increased synthesis of progesterone receptors
Glands enlarge and spiral arteries increase in number
Cervical mucus thins and forms channels to facilitate sperm entry
What happens during the secretory phase of the uterine cycle?
Increased progesterone levels prompt: further development of endometrium glandular secretion of glycogen (food for bebe) formation of cervical mucus plug increased basal body temperature
What happens in the uterus when fertilization does not occur? (5)
Corpus luteum degenerates and progesterone levels fall
Spiral arteries kink and spasm then relax and open wide
Endometrial cells begin to die
Rush of blood fragments, weakened capillary beds, and functional layer sloughs
Release of bloos, serous fluid and cellular debris during menses
How does the PSNS modulate female sexual response?
PSNS responsible for arousal and desire
Initiated by touch and psychological stimuli
Erection of clitoris, vaginal mucosa, and breasts
Bartholin’s gland secretions lubricate the vestibule
How does the SNS modulate female sexual response?
Responsible for orgasm
accompanied by muscle tension, increased heart rate and blood pressure, and rhythmic contractions of uterus
No refractory period after an orgasm
Not essential for conception
What is the SRY and what does it do?
Sex-determining region of Y chromosome
Initiates testes development and maleness
Without the SRY, sex defaults to female
When do gonads develop? What happens first in sexual differentiation?
Develop ~5th week Mesonephric ducts (male) form medial to paramesonephric ducts
How do we go from sexually indifferent to female at 5 weeks?
Genital tubercle turns into the glans clitoris
Urethral folds become the labia minora
Labioscrotal swelling becomes the labia majora
How do we go from sexually indifferent to male at ~5weeks?
Genital tubercle becomes the glans penis
Urethral folds become part of the inside of the penis
Labioscrotal swellings become the scrotum
How do gonads descend 2 months before birth?
Testosterone stimulates migration of testes towards scrotum. Gubernaculum doesn’t get longer as the fetus grows, so they get pulled down. At birth, gubernaculum contracts, pulling the testes through abdominal musculature and into the scrotum
Ovaries descend, but are stopped at pelvic brim by the broad ligament
What is the first sign of puberty in boys?
Enlargement of testes, pigmentation of scrotal sac. Happens around 10-15
What is the first sign of puberty in girls?
Breast budding
Areolar hyperplasia with small amount of breast tissue
